Forms implementation for %HTML.Trusted. Some backend changes:

* Added Charsets and Character attribute types
* Fix a heavily recursive form of ContentSets, this allows a content-set
  to include another content-set which includes another content-set, and
  so forth.

Signed-off-by: Edward Z. Yang <edwardzyang@thewritingpot.com>

tests/HTMLPurifier/AttrTransform/InputTest.php

@@ -0,0 +1,93 @@
+<?php
+
+class HTMLPurifier_AttrTransform_InputTest extends HTMLPurifier_AttrTransformHarness
+{
+    
+    function setUp() {
+        parent::setUp();
+        $this->obj = new HTMLPurifier_AttrTransform_Input();
+    }
+    
+    function testEmptyInput() {
+        $this->assertResult(array());
+    }
+    
+    function testInvalidCheckedWithEmpty() {
+        $this->assertResult(array('checked' => 'checked'), array());
+    }
+    
+    function testInvalidCheckedWithPassword() {
+        $this->assertResult(array(
+            'checked' => 'checked', 
+            'type' => 'password'
+        ), array(
+            'type' => 'password'
+        ));
+    }
+    
+    function testValidCheckedWithUcCheckbox() {
+        $this->assertResult(array(
+            'checked' => 'checked',
+            'type' => 'CHECKBOX',
+            'value' => 'bar',
+        ));
+    }
+    
+    function testInvalidMaxlength() {
+        $this->assertResult(array(
+            'maxlength' => '10',
+            'type' => 'checkbox',
+            'value' => 'foo',
+        ), array(
+            'type' => 'checkbox',
+            'value' => 'foo',
+        ));
+    }
+    
+    function testValidMaxLength() {
+        $this->assertResult(array(
+            'maxlength' => '10',
+        ));
+    }
+    
+    // these two are really bad test-cases
+    
+    function testSizeWithCheckbox() {
+        $this->assertResult(array(
+            'type' => 'checkbox',
+            'value' => 'foo',
+            'size' => '100px',
+        ), array(
+            'type' => 'checkbox',
+            'value' => 'foo',
+            'size' => '100',
+        ));
+    }
+    
+    function testSizeWithText() {
+        $this->assertResult(array(
+            'type' => 'password',
+            'size' => '100px', // spurious value, to indicate no validation takes place
+        ), array(
+            'type' => 'password',
+            'size' => '100px',
+        ));
+    }
+    
+    function testInvalidSrc() {
+        $this->assertResult(array(
+            'src' => 'img.png',
+        ), array());
+    }
+    
+    function testMissingValue() {
+        $this->assertResult(array(
+            'type' => 'checkbox',
+        ), array(
+            'type' => 'checkbox',
+            'value' => '',
+        ));
+    }
+    
+}
+